The present invention relates generally to data collection devices adapted for reading bar codes and other dataforms, and more particularly to a micro reader scan engine with a prism.
Portable data collection devices are widely used in the manufacturing, service and to package delivery industries to perform a variety of on-site data collection activities. Such portable data collection devices often include integrated bar code dataform readers adapted to read bar code dataforms affixed to products, product packaging and/or containers in warehouses, retail stores, shipping terminals, etc. for inventory control, tracking, production control and expediting, quality assurance and other purposes.
Bar code dataforms come in a variety of different formats including one and two dimensional bar codes, matrix codes and graphic codes, as well as words and numbers and other symbols, which may be printed or etched on paper, plastic cards and metallic and other items. For example, a one dimensional bar code dataform typically consists of a series of parallel light and dark rectangular areas of varying widths. The light areas are often referred to as xe2x80x9cspacesxe2x80x9d and the dark areas as xe2x80x9cbarsxe2x80x9d. Different widths of bars and spaces define different characters in a particular bar code dataform.
Data originally encoded in a dataform is recovered for further use in a variety of ways. For example, a printed bar code may be illuminated to derive reflectance values which are digitized, stored in buffer memory and subsequently decoded to recover the data encoded in the bar code. The printed bar code may be illuminated using a laser, an array of LEDs, ambient light, or the like. The light reflected from the printed bar code typically is captured using a photosensor such as, for example, a CCD detector, CMOS detect, etc, which may take the form of a sensor array integrated circuit including a plurality of such devices.
As data collection devices are used in more specialized applications, it is desirable to scan bar codes and other dataforms from different angles. Conventional scan engines include an image sensor component with an aperture adapted to receive incoming light from a scanned dataform. The light typically passes through an opening in the housing of the scan engine, and the housing may further include a protective cover for the opening. The trend in such devices is toward smaller and smaller packages, as a result of which it is desirable to reduce the size of the scan engine housing opening through which incoming light from a dataform enters. However, the image sensor components used in the data collection device scan engine may be too large to directly receive incoming light from a scanned dataform through a reduced size housing opening. Although the size of the aperture on such an image sensor may be reduced, the footprint of the integrated circuit on which the sensor aperture resides remains relatively large. Custom image sensor integrated circuits may be developed, however, it is desirable to use existing image sensor components to keep the data collection device scan engine cost low. Thus, there remains a need for a data collection device scan engine which may successfully scan dataforms from an angle using existing image sensor components through a reduced size housing opening, and which may scan bar code dataforms at an angle.
The present invention includes a scan engine for use in a data collection device, which minimizes or overcomes the above mentioned problems and shortcomings encountered in conventional scan engines. The invention further provides a method for producing a scan engine and a scan engine image sensor assembly which further address these shortcomings.
In accordance with an aspect of the present invention, there is provided a scan engine which includes a housing or enclosure with an opening for receiving light from a scanned dataform, an image sensor with an aperture, the image sensor being located within the housing and operative to sense light entering the aperture, and a prism located within the housing and adapted to receive light from the opening along a first path and to provide at least a portion of the received light to the aperture along a second path. In order to utilize existing image sensor integrated circuits, the prism allows the image sensor aperture to be mounted in the housing at an angle to the housing opening, which may be 90 degrees, whereby the second path is perpendicular to the first path. The invention thus allows the use of existing image sensor integrated circuits which may have a component width which is wider than the desired housing opening, in order to provide a reduced size scan engine in which existing image sensor components may be employed.
The prism may include a first planar face generally perpendicular to the first path and a second planar face generally perpendicular to the second path. In addition, the second face may be mounted on the aperture. The first face of the prism may be mounted proximate the opening located in a first wall of the housing. In this fashion, the prism may further operate as a protective cover for the housing opening, for example, wherein the first face of the prism is further adapted to cover the opening. In addition, the front surface of the prism may have a spherical convex shape, so as to serve as an imaging lens, and to thereby further reduce the scan engine cost and size. Moreover, the prism may be adapted to provide a seal around the opening of the first housing wall. Thus, an additional window or other protective cover for the housing opening is unnecessary, the elimination of which advantageously reduces the light signal losses associated therewith, and reduces manufacturing and assembly costs.
According to yet another aspect of the invention, there is provided a method for producing a data collection device scan engine. The method includes providing a housing with an opening for receiving light from a scanned dataform, mounting an image sensor within the housing, the image sensor having an aperture and being operative to sense light entering the aperture, and mounting a prism within the housing for receiving light from the opening along a first path and providing at least a portion of the received light to the aperture along a second path. The prism may comprise a first planar face generally perpendicular to the first path and a second planar face generally perpendicular to the second path, wherein the method may further include mounting the second face on the aperture. This may be accomplished, for example, using a low loss transparent adhesive. In this way, no gap exists between the second face of the prism and the image sensor aperture, thus further reducing incoming light signal loss.
In addition, where the opening is located in a first wall of the housing, the method may include locating the first face of the prism so as to cover the opening. Moreover, where a seal is desirable between the interior and exterior of the scan engine housing, the method may further include providing a seal around the opening of the first enclosure wall using the first face of the prism. The method thus eliminates additional housing windows associated with conventional scan engines, and the losses associated therewith.
According to still another aspect of the invention, there is provided a data collection device scan engine image sensor assembly. The assembly includes an image sensor having an aperture and being operative to sense light entering the aperture, and a prism mounted on the aperture and adapted to receive light along a first path and to provide at least a portion of the received light to the aperture along a second path. The prism may comprise a first planar face generally perpendicular to the first path and a second planar face generally perpendicular to the second path, wherein the first planar face may be further adapted to cover an opening in a scan engine housing. In addition, the first face of the prism may be further adapted to provide a seal around the opening of the scan engine housing.
To the accomplishment of the foregoing and related ends, certain illustrative aspects and implementations of the present invention are hereinafter described with reference to the attached drawing figures. The following description and the annexed drawings set forth in detail certain illustrative applications and aspects of the invention. These are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Other aspects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.